Road pavers with wheeled chassis are characterized by their mobility and versatility in comparison with those with crawler tracks. The wheeled chassis of road pavers are usually equipped with a permanent rear-wheel drive and an additional front-wheel drive, which can be selected when needed, e.g., for increasing traction in working operation. It is difficult to ensure optimal traction in the case of external influences such as different frictional conditions for example, changing axial load of the front axle, etc, so that a slip-free drive with maximum tractive power is achieved.
So-called “load-sensing systems” have prevailed in the area of hydraulic drive systems which are usually used for construction machines. The pump pressure is controlled in such a way for minimizing power losses and for the required supply of several hydraulic consumers in such a way that a constant excess pressure is maintained over the consumer with the highest load. This excess pressure, which is typically between 20 and 30 bars, is usually set via the spring pretension in the actuating cylinder of the variable displacement pump. There is a demand to further reduce the power loss which is composed of the excess pressure and the transport stream.
Road pavers are known for limiting the drive slip which recognize a deviation of the actual speed from the reference speed by means of continual monitoring of the speed for each wheel, and optionally counteract this by speed limitation. It is disadvantageous in this respect that the complexity of the sensor system and the control is too high.
The present invention is therefore based on the object of optimally controlling the tractive power of the permanent or optionally selectable front wheel drive and to actively limit at the same time any occurring wheel slip in the front wheels. It is further an object of the present invention to reduce the complexity of the control and also the costs.